National Geographic photographer Joel Sartore has a mission: to shoot (with a camera) Earth's endangered species in a studio setting, so that human viewers are forced to confront exactly who's going extinct face-to-face. So far, Joel's photographed 1,800 species, and shooting these creatures presents its own set of challenges. Namely, his subjects love defecating on set.

Please know that we always start out with the black and white backdrops in pristine shape. The minute we put an animal on it though, things go downhill fast. Animals drag in dirt, shake off feathers and dander, and of course, often relieve themselves once they've stretched their legs a bit. I clean it up as best I can (using paper towels, napkins, and whatever) and try to finish up the shoot quickly, for good reason.

The goal here is to get an interesting shot or two and then get the critter off the background as quickly as possible. This reduces stress on the animals and thus the chances that anything bad might happen. You don't want to have to catch up a rare and delicate bird more than once just because the background got nasty. Working quickly is key. And so far, in nearly 1,800 species shot, I'm proud to say there hasn't been a serious incident yet.

On another occasion, chimps trashed the backdrop in 30 seconds flat. Here are some of the animals that were feeling more cooperative. That's a spectacled owl (Pulsatrix perspicillata) above, and here are several more of Joel's gorgeous photographs.